The present invention relates to the field of remote signaling systems, and more particularly, is directed to a nationwide radio paging system which interconnects presently existing local paging services into a nationwide network. The system permits subscribers to travel virtually anywhere in the country and continue to receive pages originated from their home service area.
The concept of a wide area paging system is not new. In fact, several such systems have been proposed and described in the prior art. One such system is described in U.S. Pat. No. 3,575,558 issued to Leyburn. The Leyburn patent discloses a paging system which is said to permit simultaneous paging in more than one geographical area. The system comprises one or more storage centers which control a plurality of transmitters located in different geographical areas. When a storage center receives a page request, it consults its internal memory to determine in which areas the subscriber desired paging service. The storage center then transfers the paging information via telephone lines to dedicated transmitters serving the areas selected for paging by the subscriber.
Other wide area paging systems are disclosed in U.S. Pat. No. 3,818,145 to Hanway and U.S. Pat. No. 3,714,375 to Stover. The Hanway patent describes a paging system which extends the paging area by broadcasting the page over a plurality of transmitters. A page request received at one transmitter site is relayed to other transmitter sites. The transmitters are then activated to transmit the page. The Stover patent is directed to a paging system which transmits paging information over existing AM broadcast stations using a non-interferring phase modulation technique. Extended area coverage is achieved due to the relatively high power used by the broadcast station.
A more sophisticated wide area paging system is disclosed in U.S. Pat. No. 4,178,476 to Frost. The Frost patent is directed to a wide area paging system which privides local-only paging as well as wide area paging. In the local-only mode, the system operates in the same manner as conventional paging systems known prior to Frost. In the wide area paging mode, however, paging service may be transferred from one location to another by a transfer command entered into the system via a telephone hook-up. Thus, all pages originated anywhere within the system are transferred to the area where the subscriber is located. Broadcast of pages is temporarily suspended while the subscriber is in transit. Any pages which originate during this period are stored and then transferred to the area to which the subscriber has relocated when paging is reinstated on his arrival. The area from which the pages originate is also identified to the subscriber when they are broadcast. When a subscriber wishes to suspend paging service prior to travelling to another location, he first dials a predetermined telephone number to access the system. On receipt of an answer tone, the subscriber dials his unique identification number followed by a "suspend" digit. The system then suspends all paging to that subscriber and stores any pages received during the suspension period. When the subscriber reaches his destination, he makes another local telephone call to access the system in that area. Upon receipt of the answer tone the subscriber dials his unique identification number and a "reinstate" digit. Paging is then resumed and any pages originated during the time paging was suspended are forwarded to the new paging system and transmitted in the new area. Subsequent pages are transferred to the subscriber in that area until paging is again suspended and transferred to another area.
Though the above-described wide area paging systems represent an improvement over the existing prior art at the time, they fail to provide a cost effective system for broadcasting pages over a wide area. For example, these systems all relay on dedicated equipment installations to process and broadcast pages. Thus, these systems cannot be easily and economically extended to cover additional service areas.